Ruthenium catalyzed hydrogenation process for obtaining aminocyclohexyl compounds



Patented Aug. '12, 1952 PROCESS FOR OBTAINING AMINOCYCLO- HEXYLCOMPOUNDS Gerald M. Whitman, New Castle, DeL, assignor to E. I. du Pontde Nemours & Company, Wilmington, DeL, a corporation of Delaware NoDrawing. Application December 15, 1949,

Serial No. 133,213

The invention relates to catalytic hydrogenation processes and moreparticularly to the catalytic hydrogenation of aromatic compoundscontaining a nitrogen atom directly attached to an aromatic carbon atom.

This application is a continuation-in-part of my co-pending applicationSerial No. 615,911, filed September 12, 1945, now abandoned.

It is known to hydrogenate aniline to cyclohexylamine with suchcatalysts as nickel, osmium, iridium and cobalt. However, even under thebest conditions with these catalysts, the yield of desiredcyclohexylamine is of the order of 30% to 50% and the cyclohexylamine isaccompanied by appreciable amounts of such undesired side reactionproducts as dicyclohexylamine, N- cyclohexylaniline, benzene, andammonia, in addition to unchanged aniline. Furthermore, no catalystshave heretofore been known that would permit the eflicient one-stephydrogenation of a nitroaromatic compound in high yields to thecorresponding cycloaliphatic amine.

It is accordingly an object of this invention to provide a new methodfor hydrogenating aromatic compounds containing a nitrogen atom attacheddirectly to an aromatic carbon atom to produce the correspondingcycloaliphatic amines. Another object is to provide. a ,new method forcatalytically hydrogenating aromatic nitro compounds in one step to thecorresponding cycloaliphatic amines. Still another object is to providea method for hydrogenating aromatic amines to the correspondingcycloaliphatic amines. Other objects will become apparent from anexamination of the following description and claims.

These and other objects and advantages are accomplished according to theherein described invention which comprises the preparation ofcycloaliphatic amines by reacting as sole reactants and aromaticcompound containing a nitrogen atom directly attached to an aromaticcarbon atom with hydrogen under pressure, at a temperature of at least20 C., over a ruthenium catalyst in which the active catalytic componentis either elementary ruthenium, a ruthenium oxide, a salt of rutheniumin which the ruthenium is in the anion, or a salt of ruthenium in whichthe ruthenium isin the cation and the anion is non-polymeric. Theseruthenium catalysts are those in which the active catalytic componentisselected from the group consisting of elementary ruthenium, rutheniumoxides, salts of ruthenium in which the ruthenium is present in theanion, and salts of ruthenium in which the anion is 11 Claims. (Cl.260-563) monomeric and the cation consists of ruthenium. These selectedruthenium catalysts permit the smooth conversion in one-step of aromaticcompounds containing a nitrogenatom attached directly to an aromaticcarbon to the corresponding cycloaliphatic amines in good yields atlower temperatures than have heretofore been used in effecting suchhydrogenations. More particularly these selected ruthenium catalystspromote the hydrogenation of nitro aromatic compounds to amino alicycliccompounds in one-step in good yields at relatively low temperatures.

In a preferred embodiment a pressure reactor is charged with theruthenium catalyst, the compound to behydrogenated, and a volatileorganic solvent. The reactor is closed, pressured with hydrogen, and thereaction mixture heated with agitation. After an amount of hydrogencorresponding to that theoretically required to effect the desiredreduction has been absorbed, agitation is stopped, the reactor allowedto cool, opened and the contents discharged and filtered to remove thecatalyst. The reaction product is isolated from the filtrate bydistillation orv by other means. known to those skilled in the art.

The examples below are submitted to illustrate and not to limit thisinvention. Unlessotherwise stated, parts are by weight.

Example I A mixture of '75 parts of nitrobenzene, '75 parts of absoluteethanol, and 2.5 parts of ruthenium oxide catalyst was placed in apressure vessel and shaken under 135 atms. pressure of hydrogen. At toC. an amount of hydrogen corresponding to the formation of aniline wasabsorbed, at which point the'reaction proceeded much more rapidly andwas exothermic to C. The total hydrogen absorption correspnded to thatnecessary for the formation of 'cyclohexylamine. The product wasdischarged from the pressure vessel, filtered to remove catalyst, andthe filtrate distilled. At 61 C./49 mm., 51 parts of cyclohexylamine,corresponding to 85% of the theoretical yield,;was collected.

The above experiment strikingly demonstrates the unique activity ofrutheniumas a low temperature catalystfor the ring and nitrogroup'reduction of aromatic nitro compounds; Thus, it is seen that anamount of hydrogen corresponding to the formation of aniline is taken upat 85 to 90 C. and atms. pressure and that thereafter the ring reductionreaction is'rapid and becomes exothermic, causing the temperat reto riseto 105 c. f

Hydrogenation of nitrobenzene in ethanol solution over an activenickel-on-kieselguhr catalyst under 120 atms. pressure brings aboutreduction of the nitro group at 100 C. in 1.1 hours, but the reactionthen stops because the aniline, and any cyclohexylamineformed, act aspoisons for the catalyst. In order to bring about reduction of thearomatic ring it is necessary to effect the reaction in a separate stepat a higher temperature. Thus, the ring hydrogenation requires aboutnine hours, even at 175C. and 200 to 300 atmospheres pressure, forcompletion.

Example If A mixture of 50.5 parts of m.-dinitrob'enzene, 125 parts ofdioxane, and 2.5 parts of ruthenium dioxide catalyst was shaken under125 atms. pressure of hydrogen. At 75 C. the pressure drop correspondedto hydrogenation of the nitro.

groups to amino groups. and at 100 C. to hydrogenation of the aromaticring. The product was filtered and distilled, giving 75% of thetheoretical yield of 1,,3-diaminocyclohexane (B. P. 95 to 97/30 mm,neutral equivalent 57.1).

The above. experiment was repeated. using; in place of the rutheniumoxide catalyst, the same amount of a platinum oxide catalyst. In thiscase the nitrogroups-were hydrogenated readily at low temperature but"there. was no more hydrogen absorption up to 200 C. Distillation of thereaction product gave only m-phenylenediamine. Hydrogenation'ofm-dinitrobenzene with nickel at 175 C. yielded only'10%-of1,3-diaminocyclohexane and with cobalt at- 225 C. the yield of1,3-diaminocyclohexane was only'8-%.

Example III A mixture of 50 parts of p.nitroaniline,. 125 parts ofabsolute ethanol and 2.5 parts of ruthenium dioxide catalyst was shakenunder 135 atms. pressure of hydrogen. The hydrogen absorptioncorresponded to hydrogenation of the nitro group at 80 to 85 C., andhydrogenation of the aromatic ring at 105 to 110 C. Distillation of theproduct gave 74% of the theoretical yield of lA-diaminocyclohexane, B.P. 90 C./22v mm, neutral equivalent 57.5.

In another experiment a mixture of 150 parts of p-nitroaniline, 300parts of dioxane and 15 parts of alloy-skeleton nickel was shaken under150 atmospheres pressure of hydrogen at 175 C. until hydrogenabsorption. ceased. After filtration of theproduct, distillation gave1,4-diaminocyclohexane corresponding" to 35% of the theoretical yield.The distillation residue contained about 45% of the theoretical amountof p-phenylenediamine.

Hydrogenation of p-nitroaniline with cobalt at 175 to 225 C. gave a 34%yield of 1,4-diaminocyclohexane.

Example I V A mixture of 46 parts of benzidine, 125 parts of dioxane and2 parts of ruthenium dioxide catalyst was shaken under 135 atmospherespressure of hydrogenat 115 C. until absorption was complete.Distillation of the filtered product gave 92% of the theoretical yieldof 4,4'-diaminodicyclohexyl, B. P. 108 C./2 mm, neutral equivalent 99.1.

Hydrogenation of benzidine over a nickel catalyst required a temperatureof 180 to 190 C. under 133 to 167 atmospheres pressure for about hoursto give hexahydrobenzidine in 38% yield.

. 4 Under these conditions no 4,4'-diaminodicyclo hexyl was obtained.

Example V A mixture of, 49,5 parts.oibisfieraminophenyl) methane, 125parts of dioxane and 0.35 part of ruthenium oxide-on-charcoal catalyst,preparedas described below, was shaken under 135 atmospheres pressure ofhydrogen at 200 C. until absorption ceased. Distillation of the filteredproduct gave of'the theoretical yield of b1501- aminocyclohexybmethane,B. P. 142 C./3 mm, neutral equivalent 105.6.

The catalyst used in the above experiment was prepared as follows-:-

Ten parts of finely divided ruthenium dioxide was fused in a nickelcrucible with about 30 parts of' sodium peroxide. The melt was dissolvedin 200 parts of distilled water and the resulting solution poured withstirring, over parts of activated powdered charcoal. Theimpregnatedcharcoal wasdried overnight at C. and powdered toafine blackdust. Analysis showed the product to. contain about 7% of ruthenium.oxide.

In another experiment palladium black was used as the catalyst for the.hydrogenation of bis(4-aminophenyDmethane. After'two hours at 200 C.under 2500.lbs./in-. hydrogen pressure the reaction. wasv stopped andthe product distilled. During this period-no pressuredrop was observedand no bis(4- aminocyclohexyhmethane was found in the product.

In still another experiment alloy-skeleton nickel was used as thecatalyst for the hydrogenation of bis(.4-aminophenyD-methane. After atotal reaction period: of 11 hours. at 200 C. and 2000 to 2600 lb./in.hydrogen pressure the reaction was stopped. No: bis(4-aminocyclohexyl)methane wasfound in the product.

In another experiment elementary cobalt was used as the catalyst for thehydrogenation of bis(4-aminophenyl)methane. After two hours at 200 C.and 2500 to 3000 lb./in. the reaction was stopped. No bis ('4-aminocyclohexylamethane was found in the reaction product.

Example V! A pressure reactor was charged with 50 parts ofbis(4-aminophenyl)methane,200 parts of dioxane and.2.05 parts. of asodium ruthenate-oncharcoal catalyst containing 7% sodium ruthenate.Thereactor was placed in an agitation rack and the. contents. agitatedand subjected to the action of hydrogen under a pressure of 1460 to 3000lb./in. at 197 to 206. C. These conditions were maintained for 136minutes, during which time there was an observed pressure drop of 4820lb./in.-. The reactor was allowed to cool, the contents discharged andfiltered to remove the catalyst. From the filtrate there was obtained4.? parts of a fraction boiling at 136 to 144 C./1.5 mm. whose. neutralequivalent was 106.4. This corresponded to a yield of bis(4-aminooyclohexyllmethane of 89.5%.

Example VII A pressure reactorwas charged with 50 parts ofbis(4-aminophen'yl)methane, 200 parts of dioxane and 7.6 parts of apotassium ruthenate-oncharcoal catalyst containing 3.63 ruthenium. Thereactor was placed in an agitating rack and the contents agitated andsubjected to the action of hydrogen under a'pressure of 1850 to 3100lbs/inf! at 207 to 240 C. These conditions were maintained for threehours, during which time there was an observed pressure drop 01' 4800lb./in. The reactor was allowed to cool and the contents discharged andfiltered to remove the catalyst. The filtrate was subjected tofractional distillation. There was thus obtained 40.8 parts of afraction boiling at 139 to 141 C./3 mm., which corresponds to a 77.5%yield of bis(4-aminocyclohexyl) methane. The refractive index of thefraction was 1.5040.

Example VIII A pressure reactor was charged with 50 parts ofbis(4-aminophenyl) methane, 200 parts of dioxane and 20 parts of aruthenium nitroso nitrate-on-alumina catalyst containing 2.4% ruthenium.The reactor was placed in an agitating rack and the contents agitatedand subjected to the action of hydrogen under a pressure of 3600 to 4500lb./in. at 140 to 152 C. These conditions were maintained for threehours, during which time there was a observed pressure drop of 3375lb./in. The reactor was allowed to cool, opened and the contentsdischarged and filtered. The filtrate was subjected to fractionaldistillation. There was thus obtained 31.4 parts of material boiling at148 to 154 C./5 to 4.5 mm., which corresponds to a 72% yield ofbis(4-aminocyclohexyl) methane. The index of refraction of this materialwas 1.5047 at 27 C.

Example IX contents discharged and filtered to remove the catalyst. Thefiltrate was subjected to fractional distillation. There was thusobtained 36.2 parts of material boiling at 131 to 144 .C./2 mm., whichcorresponds to a yield of bis(4-aminocyclohexyl) methane of 73%. Theneutral equivalent of the product was 111.4.

The ruthenium chloride-on-alumina catalyst used in the above experimentwas prepared as follows:

Ten parts of ruthenium chloride (RuCls) was dissolved in 99.78 parts ofwater at room temperature. To the solution there was added 2.86 parts ofconcentrated hydrochloric acid and the solution allowed to stand forfive hours with occasioned stirring. Thereafter the solution was addeddropwise, with stirring, to 200 parts of 8 to 14 mesh alumina. Theimpregnated alumina was transferred to a vacuum desiccator, the vacuumreleased five times and the material then dried overnight at 130 C.Analysis of the dried product showed it to contain 2.4% ruthenium byweight.

Example X A mixture of 49.5 parts of bis(4-aminophenyl) methane, 129parts of dioxane, and 2.5 parts of finely divided ruthenium dioxidecatalyst was shaken under 135 atmospheres pressure of hydrogen at 100 C.until hydrogen absorption had ceased. Distillation of the filteredreaction product gave a normally liquid bis(4-aminocyclohexyl) methanein 79.2% yield. This product boiled at 141 to 143 C./4 mm., had an N 6 Iof 1.5030 and a neutral equivalent of 105.0. The calculated neutralequivalent for C13H2BN2 is 105.2.

ExampZelXI A dioxane solution ofbis(4-aminophenyl)- methane containing13 by weight of the diamine was mixed at 300 atmospheres pressure withfrom 50 to moles of 'hydrog'enp'er moleof bis(4- aminophenyDmethane, andthe mixture passed over a ruthenium dioxide-on-charcoal catalyst,prepared as described subsequently, as a space velocity of 0.14 volumeof .bis(4-aminophenyl)- methane per volume of catalyst per hour. Thecatalyst temperature was maintained at 143 to 148 C. Ninety and sixtenths per cent of the starting material was found to be converted to amixture of bis(4 aminocyclohexyDmethanes which was liquid atroomtemperature and which had a refractive index of N of 1.5059.

The catalyst used in the above experiment was prepared as follows:

Ten parts of ruthenium dioxide was fused with 50 parts of potassiumhydroxide. Tothe fused mass there was added .10 parts of potassiumnitrate over a 5 minute period, and the mixture maintained at the fusionpoint for one hour. Thereafter it was allowed to cool and dissolved'in120 parts of distilled water. The' resulting solution was poured overactivated charcoal which had been previously washed with a 10% solutionof potassium hydroxide and dried at C. for 48 hours. The volume ratio;of solution to activated charcoal was 2:3; The impregnated charcoal wasthen heated to about 50 C., 15 parts of methanol was added, f and thecomposition dried at 110 C. The resulting composition con tained about4.5% of ruthenium dioxide.

Example XII A mixture-of 1250 parts of bis (4-aminophenyl) methane, 3234parts of dioxane, and 25 parts of finely dividedjruthenium dioxidecatalyst was placed in a pressure reactor and subjected, with stirring,to a hydrogen pressure of 1500 to 2700 1b./in. at a temperature of 105to C. These conditions were maintained for'4.5 hours, even thoughhydrogen absorptionhad ceased at the end of four hours. At the end ofthe 4.5 hour reaction period, the reactor was allowed to cool. opened,discharged, and the contents filtered to remove the catalyst. From thefiltrate there was isolated, by distillation, 1147.8 parts of bis(4-aminocyclohexyl) methane as a clear, colorless viscous liquid. The yieldof bis(4aminocyclo hexyl methane corresponded to 86.7%. The materialobtained had a boiling point of 121 C'./0.5 mm. and 123 C./0.75 mm. Theneutral equivalent was 105.25 and the refractive index, N 1.5042.

The ruthenium catalysts used in the practice of this invention consistof elementary ruthenium,

- ruthenium halides, e. g., ruthenium dichloride,

ruthenium trichloride, ruthenium tetrachloride,

reases 7v ruthenium pentafluoride, etc ruthenium sulfides, e; "e.,ruthenium disulflde, an'd' trisulfide, eta; ruthenium sulfate, etc.

Optimum results are obtained when the ruthenium catalyst is in finelydivided form. When it is desired to employ very lowcatal'ystconcentraticns, it is advisable to extend theruthenium on a support, e.g., charcoal, alumina, kieselguhr, etc. Such supportedcatalystsmay beprepared by the methods of Examples V, IX, and XE, by the methoddisclosed in U S. Patent 2,079,404, orby other methods involvingreduction of a compeund of ruthenium in the presence of a carrier subane N I The amount of ruthenium catalyst. used, calculated asmetallicruthenium, may vary Within the range of from 0.001% to by Weightof aromatic compound being reduced. The exact percentage employeddepends upon whether it is desired to. effect the reaction at a lowtemperature or whether catalyst economy'is the paramount consideration.Generally, however, the amount of ruthenium catalyst, calculated asmetallic ruthenium, will range between 0.01% and 1%. by. weight of thearomatic compound being-reduced, because within this range a properbalancebetween reaction rate and catalyst economy is attained.

The, ruthenium catalysts of this invention catalyze. the ringhydrogenation of aromatic organic compounds containing a nitrogen atomdirectly attached to an aromatic carbon atom at temperatures the rangeof20 to 150 C. and are unique in this respect. If desired, in the case ofpolycyclic aromatic amines such as, bi s(4- aminophenyl)methanajtemperatures,up to 250 C. may beemployed, "The. particular"temperature selected for the hydrogenation depends up on the methodofoperation and the type of stereoisomeric mixture of.bisi-aminocyclohexyl) methane desired. Thus, if it is. desired tooperate batchwise to produce. a liquid stereoisomeric mixture ofbis(4-aminocyclohexyl) methanes temperatures. below 130 C. are employed.If it is desired to operate continuously at very low contact time,as'shcwa by Example X'Ltemperatures up to about 150 C. can be used. Ifit is desired to produce a. normally solid stereoisomeric mixture 1 ofbis.(4-an1inocyclohexyl)methanes then temperatures above l50 0., butbelow 250 C. are used. The following simplified diagrams will aid inexplaining these phenomena. Bis( l-aminocyclohexyl)methane exists I inthree StBI'BOiSOI'llEI iC forms and all three result from thehydrogenation of his (e-aminophenyl) methane. The long horizontal linesin the diagram below represent an edge View of a cyclohexane residue.

In the hydrogenation of the piste-amino phenyl) methane at a lowtemperature, 1. e., at

u a temperature below 150 0., a bis(4-arninocycloheXyDmethane results,which is believed to consist principally of a mixture of the cis-cis andcis-trans isomers. By carrying on the hydrogenation above 150. C., orby, prolonging the time of contact between the bis(4eaminophenyl)methane and catalyst, the initial ois-cis and cis-trans i cmer. mixturee ms. to. om r zc. o h h melting trans-transform. Since the basemetalsreq'uir'ethe "use of temperatuIesaboVeZGQ" C. to induce hydrogenation ofthe aromatic nuclei in his (4-'am' inophenyl) methane, it is. clearthat. with these catalysts it is not possible to obtain an isomermixture of bis (4,-arninocyclohexyl)methe ane consisting principally ofcis cis orcis-trans forms. Thus, use of ruthenium makes possible theobtainment of bis(4-aminocyclohexyl)methane isomer mixturesnototherwiseobtainable.

While this invention has been illustrated with particular reference tothe'hydrogenation of nitroaryl and 'aminoaryl compounds, suchasnitrobenzene, di'nitrobenzene, nitroalinline, benzidine, andbis(4aminophenyl)methane,- it is to be understood that it is generic'to thering hydrogenation of all aromatic organic compounds containing anitrogen atom directly attached to an aro matic carbon atom. Examples ofsuch compounds are nitro and nitrosocompounds'such' as nitrobenzene,nitrotoluene, dinitrobenzenes', dinit'rotoluenes, 1,3,5-trinitronaphthalenes, alpha-nitronaphthalen'e, m-nitrobenzoic acid,m-nitrobenzonitrile, 2,4- dinitroanisole', 3-nit'r'o-o-cresol,o-nitrodiphenylamine, 2 -nitroresorcinol, 1-nitronaphthol-2, mnitroaniline, '5-nitro-L3-xylenol, nitrosobenzene, nitrosotoluene,m-nitro-N-methylaniline, dinitrodiphenyl, bis(4-nitrophenyDmethane,etc., aromatic amines, such as aniline, benzidine, tolidine,aminobenzoic, acids, aminobenzonitrile, N-methylaniline,N-dimethylaniline, toluidines, aminocresols, 3,5-diaminophenol,1,5-diaminonaphthalena'eto, azo, azoXy, and hydrazo compounds such asasobenzene, azoxybenzene, 2-hydroxyazobene, p-azoxytoluene,hydrazobenzene, etc., Preferred, aromatic compounds are those havingnitrogen directly attached, to an aromatic carbon atom as the solesubstituent.

Although in theexamples there have been used certain conditions oftemperature and pressure, concentration, duration of reaction, etc., itis to be understood that these values may be varied somewhat within thescope of the invention since the conditions for each experiment aredetermined by the particular compound being treated.

The process is operable at pressures ranging from atmospheric up tothemaximum permitted by' the mechanical limitations of the; equipmentused. The particular pressure conditions used in any one case dependupon such interdependent factors as method of operation, temperatureconditions employed, etc. As a rule pressures in excess of 100 lb./in.are employed because under such conditions the reaction takes place at apractical rate with good yields of desired products. Irrespective of themethod of operation no practical advantages seem toaccrue from the useof pressures above 20,000 lb./in. Most generally the process iscarried'out using pressure of from 1,000 to 10,000 lb. /in.

The process of this invention may be carried outwhile the aromaticcompound is. in a fluid condition, i. e., is either a liquid, dissolvedin an inert organic solve'ntjor in the form of a vapor. Said process isgenerally operated in the presence of an inert organic medium becausethe medium s s a heat p to thu maki it poss b to control thetemperature, more closely, and because optimum conditions for completehydrogenation are realized in solution. Usefully employable inertorganic media are alcohols such as methanol, ethanol, propanol,isopropanol, etc.; others such as-dioxane, diethyl ether, eta;hydrocarbons such as cyclohexane, etc.

spouses The process of this invention; by employing selected rutheniumcatalysts, makes possible the preparation of cyclo aliphatic amines ingood yields from the corresponding aromatic compounds in one step at lowtemperatures.

Although base metals such nickel and oobait are poisoned by cyclicamines,"ruthenium can desorb such amines readily and it is not poisonedby these amines. With the .base metals it is necessary to employ hightemperatures in order to counteract the" poisoning effect of the cyclicamines 'and this operates to decrease the yield of desired cyclic amine.The striking ability ofruthenium to catalyze the hydrogenation ofaromatic amines rapidly, at low temperatures, under non-acid conditionsis based upon its radically different surface absorption characteristicsfor cyclic amines as compared to other catalytsts. This ability todesorb cyclic amines at low temperatures distinguishes ruthenium fromall other catalysts. Thus, it is the only catalyst with which cyclicamines can be obtained under non-acid conditions at low temperatures, e.g., at temperatures below 150 0.

As many apparently widely diiferent embodiments of this invention may bemade without departing from the spirit and scope thereof, it is to beunderstood that I do not limit myself to the specific embodimentsthereof except as defined in the appended claims.

I claim:

1. In a process for obtaining an aminocyclohexyl compound byhydrogenation of an aromatic compound containing a benzene nucleus and anitrogen atom directly attached thereto, the improvement which comprisesreacting, as the sole reactants, hydrogen and said aromatic compoundcontaining a benzene nucleus and a nitrogen atom directly attachedthereto, at a temperature within the range of from 20 to 250 C., underpressure in excess of 100 lbs/sq. in., and in contact with at least0.01% by weight, based on said aromatic compound and calculated asmetallic ruthenium, of a ruthenium catalyst in which the active cataelytic component is selected from the group consisting of elementaryruthenium. ruthenium oxides, salts or ruthenium in which the rutheniumis present in the anion, and monomeric ruthenium salts in which thecation consists of ruthenium, and isolating therefrom an aminocyclohexylcompound.

2. In a process as set forth in claim 1 wherein said ruthenium catalystis elementary ruthenium.

3. In a process as set forth in claim 1 wherein said ruthenium catalystis a ruthenium oxide.

4. In a process as set forth in claim 1 wherein said ruthenium catalystissupported on a carrier.

5. In a process for obtaining an aminocyclohexyl compound byhydrogenation of an aromatic compound containing a benzene nucleus and anitrogen atom directly attached thereto, the improvement which comprisesreacting, as the sole reactants in an inert organic solvent, hydrogenand said aromatic compound containing a benzene nucleus and a nitrogenatom directly attached thereto, at a temperature within the range offrom 20 to 150 C. under pressure in excess of 100 lbs/sq. in., and incontact with at least 0.01% by weight, based on said aromatic compoundand calculated as metallic ruthenium, of a, ruthenium catalyst in whichthe active catalytic component is selected from the group consisting ofelementary ruthenium, ruthenium oxides, salts of ruthenium in which theruthenium is present in the anion, and monomeric ruthenium salts inWhich the cation consists of ruthenium, and isolating therefrom anaminocyclohexyl compound.

6. In a process for obtaining an aminocyclohexyl compound byhydrogenation of an aromatic compound containing a benzene nucleus and anitro group directly attached thereto,- the improvement which comprisesreacting, as the sole reactants, hydrogen andsaid aromatic nitrocompound, at a temperature within the range of from to 150 C. underpressure in excess of 100 lbs/sq. in., and in contact with at least0.01% by weight, based on said aromatic nitro compound and calculated asmetallic ruthenium, of a ruthenium catalyst in which the activecatalytic component is selected from the group consisting of elementaryruthenium, ruthenium oxides, salts of ruthenium in which the rutheniumis present in the anion, and monomeric ruthenium salts in which thecation consists of ruthenium, and isolating therefrom an aminocyclohexylcompound.

7. In a process for obtaining cyclohexylamine by hydrogenation ofnitrobenzene, the improvement which comprises reacting, as the solereactants in an inert organic solvent, hydrogen and nitrobenzene, at atemperature within the range of 20 to 150 C. under pressure in excess oflbs/sq. in., and in contact with at least 0.01% by weight, based on saidnitrobenzene and calculated as metallic ruthenium, of a rutheniumcatalyst in which the active catalytic component is selected from thegroup consisting of elementary ruthenium, ruthenium oxides, salts ofruthenium in which the ruthenium is present in the anion,

and monomeric ruthenium salts in which the cation consists of ruthenium,and isolating therefrom cyclohexylamine.

8. In a process for obtaining an aminocyclohexyl compound byhydrogenation of an aromatic compound containing a benzene nucleus andan amino group directly attached thereto, the improvement whichcomprises reacting, as the sole reactants, hydrogen and said aromaticamino compound, at a temperature within the range of from 20 to 0.,under pressure in excess of 100 lbs/sq. in., and in contact with atleast 0.01% by weight, based on said aromatic amino compound andcalculated as metallic ruthenium, of a ruthenium catalyst in which theactive catalytic component is selected from the group consisting ofelementary ruthenium, ruthenium oxides, salts of ruthenium in which theruthenium is present in the anion, and monomeric ruthenium salts inwhich the cation consists of ruthenium, and isolating therefrom anaminocyclohexyl compound.

9. In a process for obtaining bisfll-aminocyclohexyl) methane byhydrogenation of bis(4-amin0 phenyl) methane, the improvement whichcomprises reacting, as the sole reactants, hydrogen andbis(4-aminophenyl)methane, at a temperature within the range of from 20to 250 C., under pressure in excess of 100 lbs/sq. in., and in contactwith at least 0.01% by weight, based on said bis(4-aminophenyl)methaneand calculated as metallic ruthenium, of a ruthenium catalyst in whichthe active catalytic component is selected from the group consisting ofelementary ruthenium, ruthenium oxides, salts of ruthenium in which theruthenium is present in the anion, and monomeric ruthenium salts inwhich the cation consists of ruthenium, and isolating therefrom bis(4-aminocyclohexyl) methane.

'10. In a process as set forth in claim 9 wherein said ruthenium cat'aly ai', is a ruthenium chloride STATES PATENTS;

catalyst r Q Number Name 11. 'In'a process as set forthin claim 9wherein 1 907 820 Jaeger g g the reaction is carried out in the presenceof g Brtsich v GER M. MA 9 6 Klrget a1 Jarx. 1'7, 19 0 FOREIGN PATENTS GF 7 Number Country I Date The following references are of record in the6, 48 Netherlands un u Jurle 1 OTHER REFERENCES file of jhis; patentz.

Behr et a1; JQA. c. 332611 68, pages 129651297

1. IN A PROCESS FOR OBTAINING AN AMINOCYCLOHEXYL COMPOUND BYHYDROGENATION OF AN ORAMATIC COMPOUND CONTAINING A BENZENE NUCLEUS AND ANITROGEN ATOM DIRECTLY ATTACHED THERETO, THE IMPROVEMENT WHICH COMPRISESREACTING, AS THE SOLE REACTANTS, HYDROGEN AND SAID AROMATIC COMPOUNDCONTAINING A BENZENE NUCLEUS AND A NITROGEN ATOM DIRECTLY ATTACHEDTHERETO, AT A TEMPERATURE WITHIN THE RANGE OF FROM 20* TO 250* C., UNDERPRESSURE IN EXCESS OF 100 LBS./SQ. IN., AND IN CONTACT WITH AT LEAST0.01% BY WEIGHT, BASED ON SAID AROMATIC COMPOUND AND CALCULATED ASMETALLIC RUTHENIUM, OF A RUTHENIUM CATALYST IN WHICH THE ACTIVECATALYTIC COMPONENT IS SELECTED FROM THE GROUP CONSISTING OF ELEMENTARYRUTHENIUM, RUTHENIUM, OXIDES, SALTS OR RUTHENIUM IN WHICH THE RUTHENIUMIS PRESENT IN THE ANION, AND MONOMERIC RUTHENIUM, SALTS IN WHICH THECATION CONSISTS OF RUTHENIUM, AND ISOLATING THEREFROM AN AMINOCYCLOHXYLCOMPOUND.